Using synthetic division, what is the width of the rectangle?
5 x squared + 4 x minus 6
5 x squared + 34 x + 108 + StartFraction 306 Over x + 3 EndFraction
5 x cubed + 4 x squared minus 6 x
5 x squared + 34 x + 108 + StartFraction 306 Over x minus 3 EndFraction